Working Out on an Empty Stomach – Should You Train Fasted?

You’re probably here because you’re wondering if you should be working out on an empty stomach to get better results with your training and nutrition. Today, I will share with you the Pros and Cons of Fasted Cardio and Strength Training to help you make the best decision for YOU. As a Fitness Coach, I can tell you that there are many different things that work but not everything is suitable for everyone.

With that said, let’s dive in!

Fasting Definition

Fasting can be defined as a period of time in which we abstain from food for an extended period of time. This abstinence can either be completely avoiding all food or a partial abstinence such as avoiding certain foods. People have been fasting for various reasons for thousands of years. For example, many people fast for religious reasons. Muslims fast during the month of Ramadan, where they only eat and drink after sunset and before sunrise. Fasting is also a part of other religions such as Hinduism, Jainism, Buddhism etc.

These fasts can last up to a day or even longer in some cases.

When it comes to fitness, fasted training generally refers to training without consuming anything with calories several hours before training. Water and/or calorie-free beverages such as black coffee are permitted. In fact, not drinking water can lead to dehydration and an immediate loss in performance.

For practical purposes, most people who train fasted do it the first thing in the morning upon waking up. This means that they may not have eaten anything for 12+ hours.

Working Out on an Empty Stomach – Where did the idea come from?

If you’ve been following fitness for a while, bodybuilders and magazines have been promoting the idea of eating small, more frequent meals throughout the day instead of eating too much at once. ​ Their reasoning for this was that if you spread your calories out into smaller meals, it will allow your body to break down food and use it for energy instead of storing it as fat. Many even claimed that eating more frequent meals raises your metabolic rate.

If you’ve read my article on How to Boost Your Metabolism, you will notice that I have not mentioned meal frequency as a way to increase your metabolic rate. This is because meal frequency does not seem to affect the actual metabolic rate directly.

One of the reasons why working out on an empty stomach became popular was due to the increase in the popularity of Intermittent Fasting. Intermittent fasting is in a way, an opposition to eating small meals every 3 hours. People were seeing great results in terms of weight loss and even muscle gain while only eating about 2 meals per day.

While there are different ways people like intermittent fasting, the most popular way is to skip breakfast. This means that if you workout in the morning, you will be training fasted. ​ One of the most popular resources on the topic of Intermittent Fasting is Lean Gains by Martin Berkham. I highly recommend you check out his content. ​

Benefits of Working Out on an Empty Stomach

Increased Body Fat Utilization

Fat loss is a result of creating a caloric deficit. This simply means that you will have to consume fewer calories than you burn in order to lose weight. When your body has less energy coming in from food, it will start utilizing stored energy (body fat) from your body to make up for the difference. Theoretically, when you’re in a fasted state, your body doesn’t have energy coming in. This will force your body to rely on your own body fat stores to supply your body with the energy for training.

Stubborn Body Fat Reduction

You may be wondering – Why is it so difficult to lose the last 10 pounds?

or

” ‘Im lean everywhere but I can’t lose this belly fat?

This is what is known as Stubborn Body Fat All of us store a certain amount of fat that is harder to lose than others.

Usually, this is the belly fat for most men and around the legs and hips for most women. Stubborn body fat is usually the last to go and the hardest to lose.

The body seems to hold on to this stubborn body fat more than the rest of the fat we have in the body. When working out on an empty stomach, we have a greater chance at tapping into these stubborn body fat stores if we have no energy coming in from food.

The body needs a reason to tap into it’s own stubborn body fat stores. If we’re supplying the body with energy, the body may not have a reason to do this.

Stubborn Body Fat Supplements

One of the most effective supplements for reducing stubborn body fats is Yohimbine. In simple terms, Yohimbine can increase blood flow to these stubborn body fat areas, thereby increasing fat mobilization.

That being said, Yohimbine is only effective for fat loss in a fasted state. Having a meal will most likely make your body to produce more insulin. Insulin seems to cancel the stubborn body fat burning effects of this fat loss supplement.

Lower Insulin Levels

Insulin acts as the key which unlocks the cell to allow glucose to enter the cell and be used for energy. insulin is a hormone secreted by the pancreas in response to elevated blood levels of glucose.

​Insulin is a hormone secreted by your pancreas that helps your body regulate blood sugar levels. When we consume food, especially if it is high in carbohydrates and sugar, the body produces insulin to help transport the sugar from your bloodstream and store it into your fat cells, muscle tissue, liver etc.

For this reason, insulin is also known as a storage hormone. When insulin levels are high, the body is in fat storage mode, which is the opposite of fat burning.

When we train on an empty stomach, our insulin levels are lower and will enable the body to release fat from fat cells instead of storing it.

Time-Saving

Most of us are really busy and have a limited time to exercise. One of the top reasons people have for not working out is that they don’t have the time.

Many people can’t workout immediately after having a meal. They may have to wait 1-2 hours after eating in order to work out. This may result in a waste of time.

For people who workout in the morning, making breakfast before training may also be inconvenient.

When training fasted, we don’t need to worry about making a meal and often saves us some time.

Improved Performance for some people

One of the biggest lessons I’ve learned as a fitness Coach is to make adjustments according to individual differences.

Some people perform better when they train fasted and having may make them feel lethargic and lazy.

In addition to this, many people are not too fond of eating anyway. If someone doesn’t feel hungry before a workout, it may be better for them to train fasted.

Appetite Control

One of the biggest benefits of fasting, in general, is that it blunts appetite in most people. This may seem counter-intuitive but many people experience a reduction in hunger by fasting.

When you try fasting for the first time, you may experience hunger pangs but they will soon go away.

Our bodies are very adaptive to meal timing and frequency. If you’re used to eating every 3 hours, your body gets used to feeling hungry every 3 hours. You can adapt to a different meal frequency relatively quickly if you wanted to.

Working out makes most people feel hungry. This means that you can have a post-workout meal when you’re actually hungry and avoid eating when you’re not.

Drawbacks of Working Out on an Empty Stomach

Increased risk of Muscle Loss (Catabolism)

When we eat a meal rich in protein and carbs, it has an anabolic effect. Having a dose of protein stimulates Muscle Protein Synthesis (MPS) Having carbs (and protein) makes your body produce more insulin, which is anabolic.

If we haven’t eaten for a few hours, the rate of Muscle Protein Synthesis along with Insulin levels drop.

While one of the benefits of training on an empty stomach is increased fat burning while exercising, there is also an increased risk of muscle loss.
Just as the body utilizes more body fat when there is no energy from food available, it can also break down its own Protein (muscle tissue) if needed.

When we workout, we’re actually breaking down muscle tissue. After the workout is done, Muscle Protein Synthesis is elevated as the body utilizes the protein from food to repair and build more muscle.

When losing weight, we don’t want to do our best to preserve as much muscle as possible.

This is the difference between Weight Loss and Fat Loss

Weight Loss simply refers to how much weight we lose on the scale. It doesn’t take into consideration how much of the weight is actual fat and how much is muscle.

Fat Loss refers to maximizing how much fat we lose while maintaining how much muscle we preserve.

Have you ever seen someone who has lost a lot of weight but they don’t look very lean? They may have lost weight but their body composition may not have improved significantly.

Preserving muscle mass also has a lot of benefits in terms of maintaining a healthy metabolism.

Decreased Workout Performance

Depending on the intensity of the exercise, training on an empty stomach may lead to a significant decrease in training performance.

Intensity refers to how hard you’re training in relation to your max effort.

For example, in weight training, intensity refers to how heavy you’re lifting to your 1 rep max. If you lift a weight that is over 90% of your max, it is considered as a high-intensity exercise.

If we take the example of cardio, a sprint would be considered as a high-intensity exercise. On the other hand, walking or light jogging would be considered as a low-intensity exercise.

If you train at a higher intensity, it is heavily dependent on muscle glycogen for energy.

It is true that the body utilizes fat for energy, however, fat is a slower source of energy, which may be suitable for lower-intensity exercises, which burn through energy at a slower rate.

In addition to this, the brain primarily runs on glucose for energy. This means that when your blood glucose levels drop, the level of mental fatigue will also increase. This will also lead to a reduction in training performance.

Hypoglycemia

Glucose is the primary fuel source for the brain and the body.
When we’re in a fasted state, our blood sugar levels are lowered. Training by itself also lowers blood sugar levels. When we combine these 2 with Fasted Workouts, there is a real risk of Hypoglycemia

While this may not be a severe problem for most people, it is a real issue if you’re training hard.

Even mild hypoglycemia can cause:

Fatigue

Shakiness

Anxiety

Hunger

Irritability

Lack of focus

These are not the things you should have to deal with while training hard.

Just think about it.

If you’re hungry during your workout, do you really think you’ll be giving it your all? Probably not. To get the most out of your training, you need to be physically and mentally in the zone.

Of course, there are individual differences. Some people don’t experience the symptoms of hypoglycemia very easily. If you can go hours without eating and not feel hungry, irritable or lower in energy, you can probably train without having a Pre Workout Meal.

Not Necessary to Lose Fat

My Transformation: I’ve lost over 125 pounds without fasted training

Training fasted has some advantages in terms of fat burning but it is NOT necessary to lose fat.

Fat loss is a result of a sustained caloric deficit. This means that even if you don’t maximize fat burning during exercise, you will still utilize fat throughout the rest of the day.

Fasted Training – 8 Things to Consider

1. Body Fat Levels

If you’re relatively lean, it will be harder to lose fat and maintain muscle mass

If you’re not very lean (25%+ bodyfat) it will be easier to lose fat and maintain muscle mass

This means that if you have plenty of weight to lose, you could train fasted or you could have a pre-workout meal and it won’t make a big difference in terms of fat loss and muscle preservation.

However, if you’re lean, training fasted is a double-edged sword.

Fasted Cardio may help you reduce stubborn body fat but you may also end up losing more muscle.

2.Hunger Levels

Also, as you lose weight, hunger becomes an issue. 2 hormones responsible for hunger and energy levels are Leptin and Ghrelin. As you get leaner, your Leptin levels drop because you have less fat on your body. Since you’re eating less food, your Ghrelins levels increase, thereby making you more hungry.

If hunger becomes an issue got you as you lose weight, you may not want to train fasted.

Also, it’s possible for some people to binge eat if they starve themselves for too long. This will result in them eating more calories than they should simply because of being hungry for so long.

5. Type of Exercise

If you’re primarily doing low-intensity, Aerobic exercises such as Cardio, you can perform well fasted or non-fasted

If you’re primarily doing high-intensity, Anaerobic exercises such as weight training with heavy Squats, Bench Press, Deadlifts, Rows, Pull-ups etc, you will most likely not perform at your best in a fasted state.

Generally speaking, there are 2 types of exercises: Aerobic and Anaerobic

Aerobic Exercises are lower in intensity such as walking, light jogging, dancing, hiking, cycling, swimming. This form of training relies on oxygen for energy.

Since it is a low-intensity exercise, it also burns through energy slower and can utilize body fat efficiently while exercising.

Anaerobic Exercises are higher in intensity such as strength training or High-Intensity Interval Training. These exercises burn through energy faster than lower intensity exercises.

Anaerobic exercises rely on muscle glycogen for energy since glucose is a faster and more efficient source of energy than fat.

6. Duration of Training

If you’re doing a short workout of about 30-60 minutes, you won’t have to worry too much about fatigue, hypoglycemia, hunger etc. too much.

A longer workout, especially if it’s fasted will lead to more fatigue and hunger as it goes on.

If you’re into strength training like I am, these workouts can take a long time to complete. In fact, some of my powerlifting training sessions are over 3 hours long. Many athletes also train for longer durations for several hours a day.

Working out on an empty stomach will most likely lead to poor performance in this case. Having a pre-workout or even an intra-workout meal will be useful if the training sessions are long.

7. Duration of Fast

The longer you go without food, the worse it will be for your performance.

For example, if Person A hasn’t eaten for 6 hours and Person B hasn’t eaten for 12 hours, who do you think is going to perform better?

It’s most likely going to be person A.

You have to look at how long it has been since your last meal to determine whether you should consume a pre-workout meal or train fasted.

8. Individual Performance & Preference

As a coach, I have clients who have different preferences. Some people don’t prefer to eat and perform worse if they have a pre=workout meal.

Others get hungry and hypoglycemic easily.

Ultimately, you have to find what works for you. If you want to try training on an empty stomach, track your performance and see if there is an improvement or a decrease.

A Better Approach: Semi-Fasted Training

If you prefer to train fasted but are worried about muscle loss and feeling hungry, a solution to do this is to have a protein shake before during your workout.

While you’re technically not fasted when you do this, it is a convenient way to get some Amino Acids into your system to reduce the chances of muscle loss while losing weight.

Protein is also satiating and will help reduce hunger while you workout.

You should be hydrated while you workout anyway. A protein shake will help you stay hydrated while getting in the Essential Amino Acids at the same time.

About The Author

Hi there! My name is Anand and I'm a Fat Loss and Strength Coach. I'm also a competitive Powerlifter and Author. My goal is to help you reach your goals hether you want to lose weight, build muscle, increase strength or even feel better. Feel freet to email me at anand@underdogstrength.com